Best IDE/compiler for AVR

I'm quite new to MCU programming.
I started programming using winavr.
In win avr I've to write most of the functions myself, searching the datasheet, learning details of all registers, etc.
That's why it's slowing down my progress.
I want to learn, but i want to progress faster. (I know there trade offs...).

I need some guideline for choosing Best (and free) IDE/compiler for AVR
As i'm inexperienced it's difficult for me to decide reading tons of information and opinions in the web.

can any one please help me....
nb.: Best for me(help learning, let me proceed rather stuck with basics, free, and support in the internet)

Have you tried the Atmel Studio? It has all the registers etc. in it, nice code completion and a load of examples.
But really, you cannot do anything without reading the datasheet for the chip that you are using and I dont think there is any IDE or library that could help you with that.

Atmel Studio is free and very good integrated development environment (IDE). If you do not like it, then you could try Ultra Edit, a great "general purpose" text editing software for programmers.. you can use that and still manage your avr projects with Atmel Studio.